Multiple Subscription Blocks for one list

Case: track multiple signup forms for one list

Is this currently possible with the Drupal MailChimp module?
MailChimp allows this with their embedded forms.
And I'm currently checking out the webform_mailchimp route, not sure if that's the way to go.

To be able to track where subscriptions came from, we should be able to add multiple blocks for one list or alterations of the basic block for a list.
Tracking 'signup source' is not enough, because that always seems to be listed as 'API - Generic' using the Drupal MailChimp module.
Tracking based on signup form (Drupal Block) allows us to segment the list based on signup form / block (merge tag value)

It can be achieved by customizing a field value per MailChimp form (or Drupal Block).
Setting a hidden field value seems to do the trick, for example:
<input type="hidden" name="FORMSOURCE" id="FORMSOURCE" value="ebook1" />
or
<input type="hidden" name="FORMSOURCE" id="FORMSOURCE" value="ebook2" />
Allows one to send the corresponding ebook in the 'Welcome email', based on conditional merge tags.

Documentation

Tracking separate forms by customizing MailChimps embedded form
http://blog.mailchimp.com/tracking-signup-pages-via-the-mailchimp-embedd...

Conditional merge tags
http://kb.mailchimp.com/article/all-the-merge-tags-cheatsheet#Conditional